Electromagnetically actuated switch construction



Nov. 3, 1959 M. RIGERT ELECTROMAGNETICALLY ACTUATED SWITCH CONSTRUCTION2 Sheets-Sheet 1 Filed March 13, 1958 INVENTOR. flax Rzyert @m Mflttarng M. RIGERT Nov. 3, 1959 ELECTROMAGNETICALLY ACTUATED swncnCONSTRUCTION Filed March 13, 1958 2 Sheets-Sheet 2 INVENTOR. Max Edger:BY W fi ttorngy United States Patent ELECTROMAGNETICALLY ACTUATED SWITCHCONSTRUCTION Max Rigert, West Allis, Wis., assignor to McGraw-EdisonCompany, Milwaukee, Wis., a corporation I of Delaware Application March13, 1958, Serial No. 721,140

'5 Claims. (Cl. ZOO-87) This invention generally relates to electricswitches, and particularly, to an electromagnetic switch actuator thatallows both manual and automatic operation of a switch.

Objects of this invention are to provide a novel, simple and inexpensiveautomatic switch operator: that uses but one solenoid for driving anassociated line switch open and closed; that responds without time delayafter receiving a control signal;- that minimizes lost motion; thatrequires the motivating solenoid plunger to travel only a short distancewhile executing a power stroke to the end that its air gap may be smalland its initial driving force large, which conditions lead to low totalenergy consumption, and particularly, to low inrush current.

A further object is to provide an improved electromagnetic switchactuator that enables manual and automatic operation of the switchwithout one operating means burdening or mutually interfering with theother.

A general object of this invention is to provide a new and improvedautomatic switch. More specific objects will appear from time to timethroughout the course of the ensuing specification.

The switch construction constituting the subject of this invention isgenerally applicable where it is desired to control a power line bymanual operation of the switch or by automatic operation from a remoteposition in response to a suitable control signal. One example ofautomatic operation is found where the switch is applied to control astreet lighting circuit and the actuator is caused to respond to asignal received from a photosensitive device, for example. A more commonapplication, however, is in the control of power factor correctivecapacitor banks where a number of such switches operate simultaneouslyto connect and disconnect capacitor groups in each phase in response toline power factor. In capacitor switching installations using prior artmagnetically operated switches, the inrush currents of the individualswitch operators totals such a great amount that the available controlpower must be inordinately great and protective fuses in thecontr'olcircuit must be enlarged to cope with inrush current at theexpense of adequate protection under steady state conditions.- This is'one of the disadvantages which the present invention overcomes.

In general terms the new switch actuator comprises an electromagnet andarmature plunger which executes a power stroke when moving in onedirection under magnetic influence and which is returned to its originalposition under the influence of a return spring. Consecutive strokes ofthe plunger alternately close and open the switch through the agency ofa T-link which engagesa switchoperating lever and transfers from one armof the lever to another after each successive operation. The springs foreffecting transfer of the T-linkon the switch also return the plunger toits original position. A limit switch is provided for-'deener'gizing theelectromagnet at the end of its power stroke and for maintaining itdeenergized until the next control signal is applied to the actuator.

ice

The switch to which the actuator is applied may take many forms, but theone here chosen for illustration is of the type that is enclosed in anoil-filled tank and which includes line contacts that are spring-biasedopen but latched closed. I

An embodiment of the invention will now be discussed in greater detailin reference to the drawings, in which:

Fig. l is an elevational view of an oil switch on which is mounted theswitch actuator of the invention, the latter being shown in inactivecondition and prepared to open the switch;

Fig. 2 shows the actuator of Fig. 1 as it appears at the end of anopening stroke;

Fig. 3 is a fragmentary view of the actuator corresponding with Fig. 1,but showing it prepared to close the oil switch; I

Fig. 4 is a partial sectional view taken on a line corresponding with4"4' in Fig. 3; v

Fig. 5 is a wiring diagram of the switch actuator and a control station;7

Fig. 6 is a vertical sectional view taken throughthe oil switch havingits line contacts in closed position after the switch has been rotatedwith reference to Fig. 1; and,

Fig. 7 illustrates the switch of Fig. 6 in open position.

Refer now to Fig. l which shows a switch tank 1 provided with a cover 2upon which is supported a line bushing 3. In a single phase switch thereare in fact two such bushings 3, one for leading current in and theother out of thetank. The tank is provided with a mounting bracket 4 forsupporting it above ground level on a power pole, a metallic structure,or other suitable means, not shown.

On tank 1 there is fastened by any suitable means, an actuator housing5' into which extends an operating shaft 6 of the oil switch, seeparticularly Fig. 4. It will be understood that rocking of shaft6through a limited angle in one direction will close the oil switch asin Fig. 6 and rocking it in an opposite direction will open the switchas in Fig. 7.

For rocking switch shaft 6 by means of the actuator, there is fastenedto the shaft a double-armed lever comprising a pair of parallel,generally triangular congruent plates 7 and 7. The plates 7 and '7 maybe secured in spaced parallelism with each other by means such asshouldered anchor pins 8' and lug pins 9 which span the space betweenthe plates. These pins may be welded or peened in order to secure them.

The rear plate 7 of double-armed lever has one end of a coupling sleeve10'welded onto it at 11. The other end of sleeve 10 is pinned at 12 toswitch shaft 6. It is thus seen that lever assembly 7' and 7 is directlyconnected to the switch shaft 6 for the purpose of rocking the latter inopposite angular directions.

The motivating force for double-armed lever 7, 7 is derived from anelectromagnetic operator comprising a magnetic frame 15, a plunger 16and a coil 17. The magnetic frame may belaminated but it is here shownas being made of solid iron for simplicity. Coil 17 is wound on an insulating spool 18 that has a central bore 19 in which the magneticarmature or plunger 16 may reciprocate. As viewed in Fig. 1, plunger 16is in a first or uppermost position, corresponding with coil 17 beingdeenergized, and with an air gap 20 underneath and between it and amagnetic guide plug 21. Impact between the plunger 16 and plug 21 may beabsorbed by a resilient washer 22, as seen in Figs. 1 and 2. Axialmovement of plunger 16 is guided and aligned by a guide pin 23 extendingfrom the bottom of the plunger through an appropriate hole in" guideplug 21.

Pivotally attached on a pivot pin 24 near the upper end of plunger 16 isa link 25 having generally a T-shaped configuration. It will be evidentfrom viewing Fig. 2 particularly that the upper end of plunger 16 issuitably slotted at 26 for accommodating the lower pivot end of theT-link so that the latter may swing through a limited angle in a planelying normal to the axis of pivot pin 24. As explained earlier,double-armed lever plates 7, 7' are congruent and spaced. This is forthe purpose of admitting between them the upper portion of T-link 25 asis clearly evident in Fig. 4 and in Fig. 2 where the front plate 7constituting the double-armed lever is broken away.

The upper or head end of the T-link is provided with oppositelyextending bevelled shoulders 30, 30 which are adapted to engage lug pins9, 9' and thereby drive doublearmed lever assembly 7, 7' when plunger 16descends under magnetic influence.

In Fig. 1, where the actuator is shown deencrgized, it will be seen thatshoulder 30 of the T-link is engaged with the right lug pin 9 of thedouble-armed lever assembly 7, 7'. When the plunger 16 is attracteddownwardly as in Fig. 2, it is seen that T-link 25 rotates lever 7, 7through a clockwise angle. In order to transfer T-link 25 so that itsshoulder 30 disengages lug pin 9 and so that its other shoulder 30engages lug pin 9', there is provided a pair of angularly disposedsprings 31 and 31 whose common ends are attached to a pin 32 on T-link25 and whose remotely opposite ends diverge and are attached nearopposite extremities of the double-armed lever assembly 7, 7 by means ofanchor pins 8. Springs 31, 31' serve the double purpose of retractingplunger 16 after'a power stroke and of transferring the T-link as justexplained. Thus, it may be seen that when the T- link has been moveddownwardly from its Fig. 1 to its Fig. 2 position for opening the oilswitch, spring 31' which was relaxed in Fig. 1 becomes extended as inFig. 2 so that when coil 17 is deenergized, spring 31' will retract link25 and plunger 16 upwardly and cause shoulder 30' of the link to engagewith the lug pin 9', thereby terminating in a condition represented byFig. 3.

It will be understood, of course, that the next successive energizationof coil 17 causes double-armed lever 7, 7 to rotate counterclockwisefrom its Fig. 3 position and to again be restored to its Fig. 1 positioncorresponding with closing of the line switch.

In order to deenergize solenoid coil 17 and cut off its control signal,the actuator is provided with a single pole, double throw, limit switch33. Limit switch 33 is provided with an operating arm 34, see Fig. 1,which is spring-biased in a counterclockwise direction from the positionin which it appears in that figure. Referring further to Figs. 1 and 4it will be seen that the back plate 7' of the double-armed lever carriesan axially extending limit switch pin 35 which drives limit switch arm34 in opposition to its biasing spring when the line switch is closed asin Fig. 1. When coil 17 is energized to effect an opening power strokeof the actuator as has taken place in Fig. 2, it will be seen that limitswitch pin 35 has swung clockwise and clear of arm 34. The limit switch33 does not operate nor does its arm 34 change position until the end ofthe plunger stroke following movement of the plunger 16 from its Fig. 1to its Fig. 2 position because the limit switch arm 34 is restrainedtemporarily by a leaf spring 36 whose end bears against the limit switcharm in Fig. 1. When pin 35 has oscillated from its Fig. 1 to its Fig. 2position, which corresponds with the end of the plungers power stroke,it strikes leaf spring 36 and allows limit switch arm 34 to swing underand be held by it as is clearly evident in Fig. 2.

In Fig. 3 it will be seen that the actuator is prepared for its nextswitch closing power stroke, and that limit switch pin 35 may swingcounterclockwise through a limited angle before it strikes limit switcharm 34 to transfer the latter back to its Fig. 1 position. Thus the fullpower of the electromagnet coil 17 is applied to plunger 16 when eitheropening or closing the oil switch and the coil is finally deenergized bythe limit switch 33 when the operation is completed.

Although a connecting terminal block 38 is shown in Figs. 1 and 2, thewiring has been omitted for it may be understood by referring to theschematic circuit diagram of Fig. 5. In this figure is seen a pair ofcontrol voltage lines 39 feeding into a control station 40 housing asingle pole, double throw, control switch 41. The movable contact arm 42of the control switch is adapted to contact one of the control switchterminals 43 or 44 whenever it is placed in such position for operatingthe actuator and to return to a neutral center between terminals 43 and44 thereafter. Jumper wires 45 connect control switch 41 with thestationary terminals of limit switch 33. schematically, the movablecontact arm of the limit switch is serially connected with the solenoidcoil 17 which is connected to one side of the control voltage source bymeans of a wire 39. In Fig. 5 the pin 35, leaf spring 36, and lever 7which control limit switch 33 are represented by a broken lined symbolidentified by the reference numeral 46. Switch 41 is only exemplary forit may be replaced by a contact making voltmeter, for example, or anymomentarily contacting switch. However, in conjunction with an oilswitch that can be operated manually, as will appear below, it ispreferable that arm 42 return to a neutral, switch open position inorder to avoid closing the solenoid 17 circuit when the limit switch 33shifts contacts as a result of lever 7 rocking during manual operation.

The electrical functions of the circuit in Fig. 5 are similar to athree-way switch circuit. For example, if switch arm 42 in the controlstation is transferred from its shown position to one of contact withstationary contact 44, power will be delivered through the closed limitswitch 33 and through solenoid coil 17. By means which have already beendescribed, when solenoid coil 17 has moved plunger 16 to the end of itsstroke, the limit switch 33 will be transferred to contact its otherstationary terminal and thereby open the circuit to the solenoid whileat the same time preparing it for its next successive operation. Whencontrol switch 41 is momentarily trans.- ferred back to its Fig. 5position, of course, limit switch 33 will execute a converse motion andbe restored to the position in which it is shown.

One form of line switch which may be operated by the switch actuatordescribed above is shown in some detail in Figs. 6 and 7 as an oilswitch housed in metal tank 1 which is filled with oil to the levelindicated by the dashed line 48. The switch construction includes a pairof insulating plates 49 one of which is shown, but which is inparallelism with another and supports a pair of stationary contacts 50that are adapted to be bridged for closing a circuit by a conductivebridging bar 51. Bridging bar 51 is mounted on an insulating lever 52that pivots on a pin 53 spanning between adjacent insulating plates 49.Lever 52 is connected by a pin 54 to a long, upwardly extending,insulating link 55. The upper end of insulating link 55 is provided witha shaft whose end 56, extending toward the observer, is round on oneside and flat on the other and whose midsection effects a pivotalconnection between the insulating link 55 and a rocker arm '57 that isloosely journalled on main shaft 6. As viewed in Fig. 6, flattenedportion 56 is engaged with a notch 58 on a latching arm 59 that isspring-biased in a clockwise direction by a torsion spring 60surrounding its stationary pivot pin 61. By this means switch link 55and lever 52 are restrained in their switch closed posi tion of Fig. 6in opposition to an opening spring 62 that connects to link 55 at oneend and is anchored at its upper end at any suitable place on tank cover2. In Fig. 7 it will be seen that link 55 is unlatched and the switchopened under the contracting influence of opening spring 62.

In Figs. 6 and 7 may be seen, in phantom outline, a

manual. operating handle 63- that is. pinned. to: andv swings with;switch shaft 6. Actually the. handle is. afiixed. to the end of theshaft that. is. nearest the: observer and it would not appear in: thesesectional. views. Shaft 6'may be rotated by manipulating operating;handle 63 or by the influence of the actuator described above-with anefiect to. be described in the next: paragraph.

Inside the switch. tank 1, shaft 6 carries a short arm 64 that is pinnedon the shaft. It may be seen in Fig. 6 that: loosely journalled rockerlever 5-7 is connected to arm 64 through the agency of a, short coilspring 65 which holds arm 64 and lever 57. in abutment. When shaft 6 isrotated from its Fig. 6 position, either by the actuator or by pullingoperating handle 63 downwardly, coil spring65 is stressed whileshortzarnr 64 turns counterclockwise until it strikes latch arm 59 as inFig. 7 and allows the release of flattened shaft 56 and consequentopening of the switch contacts 50, 5.1. During this opening movement andbefore the latch is disengaged, spring 65 is loaded and thereby servesto assist opening spring 62 in quickly accelerating the switch parts toopen position. To limit opening movement, short arm 64 is provided witha stop extension 66 that strikes a suitable abutment on the tank cover 2as may be seen in Fig. 7. As explained above, the switch of Figs. 6 and7 operates similarly whether shaft 6 is operated by the electromagneticactuator or by the manual handle 63. Under all circumstances, the manualhandle 63 serves to indicate the position of the switch contact arm 52.

When the oil switch is operated manually, the double armed leverassembly 7, 7' of the actuator oscillates through the angle that may beseen by comparing Figs. 1 and 2, and the T-link 2/5 is transferredbetween alternate lug pins 9, 9 in a manner similar to what happens ifthe switch were operated by the actuator. Likewise, the limit switch 33is actuated to a new position by pin 35 regardless of how the switch isoperated so that it is always prepared for the next response to acontrol signal.

In summary, a single solenoid electromagnetic switch actuator has beendescribed that is characterized by small lost motion as a result of theT-link 25 being engaged with lugs 9 or 9' whenever an operating strokeof plunger 16 is about to be commenced. Further, the air gap 26 beneaththe solenoid plunger v16 may be made relatively small by virtue of itsWhole travel being effective to rock double-armed lever assembly 7, 7'and operate the oil switch in the absence of lost motion. Because of thesmall permissible air gap, the flux leakage of the solenoid operator islow, even at the beginning of the plunger stroke, and accordingly,inrush current is minimized.

Having disclosed a preferred embodiment of the invention, many obviousembodiments will now appear to those versed in the art. Therefore, it isto be understood that the specific details of construction disclosed arefor illustration, not limitation, except as made necessary by the scopeof the appended claims.

It is claimed:

1. A switch actuator including an armature electromagneticallyattractable from a first position to a second position, switch shaftmeans adapted to be driven in alternate angular directions by successiveoperations of the armature, lever means operatively coupled with saidshaft and having arms extending to opposite sides of the shaft axis,link means pivotally attached at one end to said armature and releasablyengaged without lost motion at its other end with one of said lever armswhen said armature is in first position and while moving to secondposition under magnetic influence, and spring means connecting saidlever and said link means for biasing said link means from engagementwith one leverarm into engagement with the other lever arm when themagnetic influence on the armature is relieved and also for biasing saidarmature toward said first position.

2. A switch construction comprising separable switch 6. contacts,opening spring means biasing said switch. contacts toward v separation,.latch means operatively engaged with one contact. to holdv the sameunseparated in. op.- positionto-the opening springmeans, a switchoperating shaft coupled: to said one switch contact. for closing theswitch when rotated. in one direction against the bias of. said opening:spring, latchrelease lever meanscarried on said shaft for releasing saidlatch when the shaft is rotated in another direction, an"electromagnetic switch actuator including a double-armed lever affixedon said operating shaft, lug means on. said double-armed lever atoppositesides of itsrotational axis,- a generally FT-shaped link. meansdisposedv between said lug means, a. reciprocating magnetic. plunger towhich said link is pivotally attached, apair of. springs. having theircom- .mon ends connected to said T-shaped link means and their otherends respectively connected to said doublearmed lever at opposite sidesof its rotational axis, a solenoid coil for attracting said plunger whenenergized, whereby said link means will drive said double-armed lever inone direction and load one of said pair of spring means, said solenoidcoil when deenergized allowing said one spring to transfer said linkmeans to a new position on said double-armed lever and to return saidplunger to its original position.

3. A switch actuator including a solenoid coil and a magnetic plungerthat is movable between unattracted and attracted positions, a switchoperating member adapted to be driven to alternate angular positions bysuccessive attractions of said plunger, a double arm lever attached tothe switch shaft means for swinging in a plane substantially normal tothe axis thereof, link means pivotally attached to said plunger forswinging movement to opposite sides of the plunger axis, lug means oneach lever arm alternately releasably engageable with said link meansfor rotating the lever means when said plunger is attracted, transferspring means connected between said lever and said link means forbiasing the latter at an angle with respect to the plunger axis and intoengagement with one of said lug means when the solenoid coil isenergized and for retracting said lin'k means into engagement with theother of said lug means when said plunger returns to its unattractedposition, said transfer spring means also biasing said plunger towardits unattracted position whereby said plunger will return to itsunattracted position when said solenoid coil is de-energized.

4. A switch actuator including switch shaft means rotatable in oppositedirections between switch open and switch closed positions, a normallyde-energized solenoid coil and a magnetic plunger therein, a double armlever attached to said switch shaft means for swinging in a plane normalto the axis thereof, lug means on said double arm lever at oppositesides of its rotational axis, a generally T shaped link means disposedbetween said lug means and having one end pivotally attached to saidplunger, a pair of springs having their common ends connected to said Tshaped link means and their other ends respectivelyconnected to saiddouble armed lever at opposite sides of its rotational axis, said linkmeans driving said double armed lever in one direction and loading oneof said pair of spring means when the plunger is attracted upon theenergization of said solenoid coil, said one spring transferring saidlink means to a new position on said double arm lever and returning saidplunger to its original position when said solenoid coil istie-energized.

5. A switch construction comprising separable switch contacts, openingspring means biasing said contacts toward separation, latch meansoperatively engaging one of said contacts to hold the same unseparatedin opposition to the opening spring means, a switch operating membercoupled to said contacts for closing said switch when operated in onedirection against the bias of said opening spring, latch release meanscoupled to said member for releasing said latch when said switchoperating 7 member is operated in a second direction, an electr0-magnetic switch actuator including a doubled armed lever afiixed to saidoperating member, lug means on said double arm lever at opposite sidesof its rotational axis, a generally T-shaped link means disposed betweensaid lug means, a reciprocating magnetic plunger to which said link ispivotally attached, a solenoid coil for attracting said plunger whenenergized, opposite Portions of said T-shaped link being alternatelyreleasably engageable with said lug means for rotating said lever inopposite directions in response to movements of said plunger in onedirection and transfer spring-means conneeted between said lever andsaid link means for biasing the latter at an angle with respeet'to theplunger axis and into engagement with one lug means when said 152,046,401

8 solenoid coil is energized and for retracting said'link means intoengagement with the other lug means upon the de-energization of saidsolenoid means, said transfer spring means'also returning "said plungerto its initial position when said solenoid coilis de-energized.

References Cited in the file of this patent UNITED STATES PATENTS1,176,984 Philpott Mar. 28, 1916 1,192,531 Kitchen July 25, 19161,468,701 Despard Sept. 25, 1923 1,658,511 Bruynis Feb. 7, 19281,916,360 Crane July 4,1933

Moore i July 7, 1936

